The goal of this study is to investigate the role of sympathetic-adrenal medullary (SAM) and hypothalamo-pituitary-adrenal (HPA) systems in mediating the addictive effects of cocaine. Six male subjects will be assigned to either cocaine (32 mg/70 kg iv) or placebo (saline iv) treatment for the first experimental session and the alternative treatment for the second session. Several endocrine (serum epinephrine, norepinephrine and cortisol levels), physiological and subjective endpoints will be measured. We hypothesize that cocaine administration will lead to increased blood levels of norepinephrine, epinephrine and cortisol in cocaine dependent subjects.